1. Field
The disclosure relates to a substrate unit and a display module and, in particular, to a substrate unit and a display module applied to a display apparatus.
2. Related Art
Liquid crystal display (LCD) apparatuses have advantages over cathode ray tube (CRT) display apparatuses such as low power consumption, less heat, light weight, and no radiation. Because of these advantages, LCD apparatuses have been widely used in various electronic products and gradually are replacing traditional CRT display apparatuses.
In general, an LCD apparatus includes an LCD panel and a backlight module. The LCD panel has a thin film transistor (TFT) substrate, a color filter (CF) substrate, and a liquid crystal (LC) layer sandwiched between the two substrates. Additionally, the LCD panel includes a plurality of pixels that are formed in array configured by the substrates and the LC layer. The backlight module causes the light emitted from a light source to be evenly distributed to the LCD panel, and the pixels can thus display desired colors to form an image.
FIG. 1 illustrates a display panel 20 including a CF substrate 21, an LC layer 22, and a TFT substrate 23. The LC layer 22 is sandwiched between the CF substrate 21 and the TFT substrate 23, and the LC layer 22 contains LC molecules 221 and spacers 222.
The CF substrate 21 mainly includes an alignment layer 211, a transparent electrode layer 212, a passivation layer 213, a color filter layer 214, and a light-shielding layer 215, which are sequentially disposed on a side of a glass plate 216. In addition, the CF substrate 21 further includes a polarizing layer 217 which is disposed on the other side of the glass plate 216. The TFT substrate 23 mainly includes an alignment layer 231 and a semiconductor layer 232, which are sequentially disposed on a side of a glass plate 233. Also, the TFT substrate 23 further includes a polarizing layer 234 which is disposed on the other side of the glass plate 233.
The light emitted by a backlight (not shown) will pass through the TFT substrate 23, the LC layer 22, and the CF substrate 21 sequentially, and images can be formed thereby. During the travelling, the light first passes through the polarizing layer 234 and gets polarized. Second, the light passes through the color filter layer 214 and then reaches another polarizing layer 217. However, because the color filter layer 214 contains a pigment composed of particles, when the light passes through the color filter layer 214, the polarization of the light that is previously polarized by the polarizing layer 234 will change due to the Mie scattering or the Rayleigh scattering by the color filter 214. Accordingly, the polarization of a portion of the light will be changed undesirably before the light passes through the polarizing layer 217. Hence, light leakage at the dark state and lower transmittance at the bright state will occur, and thus the display efficiency will be lowered.